The invention relates to an independent wheel suspension for steerable wheels of motor vehicles having a wheel bearer connected to the vehicle body by upper and lower guide wheel members.
An independent wheel suspension for steerable wheels is shown in German Examined patent application No. 1,938,850, FIG. 7, in which the wheel can be swivelled about an ideal steering axis for executing steering movements. The ideal steering axis is an intersection of two planes, each defined by an articulation point on the wheel bearer and the axes of two sets of independent guide links. When viewed from the top and from a straight-ahead travel position, the two guide links of each set are angled inward towards each other and the wheel bearer, and are connected in articulated manner to both the vehicle body and the upper wheel bearer forming a coupler. In this wheel suspension, the upper guide links, during steering and spring deflection movements of the wheel, execute cardanic movements about their body-side articulation points.
Based on the design principle of this above-mentioned wheel suspension, an independent wheel suspension has been developed and is described in German Unexamined patent application No. 3,138,850 in which, during a turning of the outer wheel in a curve, the ideal steering axis shifts towards the rear in its upper area with respect to the travel direction.
The tilting of the steering axis resulting during wheel turning is achieved by a special spatial arrangement of the two upper guide links. With respect to a plan view, the line of symmetry of the guide links, in straight-ahead travel position of the wheel, encloses an acute angle with the wheel axis and, in the travel direction, is located behind the wheel axis.
As a result of this tilting of the steering axis, the castor angle, held to zero in this wheel suspension in the straight-ahead travel position of the wheels, increases at the outer wheel in a curve. The consequently increasing castor distance ensures a good return movement of the steering.
However, for spatial reasons or because of other design specifications, it is not always possible to orient the guide links towards the rear, as in the above-reference, to such an extent that the desired effect of increasing the castor distance at the outer wheel in a curve is realized to a desired extent. Further, such a measure is not always in accord with other demands made on a wheel suspension.
It is therefore an object of the present invention to provide a wheel suspension that enables the castor distance to be increased at the wheel in a curve during wheel turning, while maintaining a specified basic arrangement for the guide links.
This and other objects are achieved by the present invention by providing a first upper guide wheel member comprising first guide links connected at articulated points to the vehicle body and the wheel bearer, and a first coupler connected between the articulated points at the wheel bearer. The first coupler is angled rearwardly from the wheel and inwardly toward said vehicle.
In a preferred embodiment of the present invention, the first coupler transverses a bisector of the angle formed by the first guide links. This angled position of the first coupler to the angle bisector of the angle formed by the guide links causes the first ideal guide articulation, defined as the connecting lines of the articulations of the two first guide links, to be displaced rearward relative to the wheel against the travel direction during the course of a wheel turning at the outer wheel in a curve. At the same time, a desired wheel camber can be achieved since the first guide articulation moves closer towards the wheel central-longitudinal plane during the course of a wheel turning.
The displacement of the ideal first guide articulation brings about the desired tilting and, if necessary, spreading of the steering axis. The required displacement of the ideal first guide articulation is achieved by the angled position of the coupler to the angle bisector in conjunction with the first guide links converging in the direction of the wheel bearer.
At the same time, the spatial arrangement of the first guide links and their longitudinal dimensions can be selected in accordance with design regulations, such that the guide links can lie in a common plane or in a skewed position relative to one another.
In a preferred embodiment of the present invention, the second lower wheel guide member is made as a triangular guide link which is connected in articulated manner to the wheel bearer via a universal joint. The second wheel member comprises two individual guide links and a second coupler which is angled forwardly and inwardly from the wheel. The advantageous result is that the second ideal guide articulation, defined as the connecting line of the articulations of the two second guide links, is displaced in a direction during wheel turning which is opposite to that of the first guide articulation and thus enables the castor distance to be optimally set.
In a preferred embodiment of the invention, the second coupler is shorter than the first coupler, as a result of which the second guide articulation, during steering movements, is displaced less than the first guide articulation.
Further objects, features, and advantages of the present invention will become more apparent from the following description when taken with the accompanying drawings, which show for purposes of illustration only, an embodiment constructed in accordance with the present invention.